This invention pertains to a disk for cleaning magnetic transducer heads in magnetic disk-reading machines having a light source and light sensor for detecting the presence of a disk. More particularly, it pertains to such a disk formed of a pair of layers of head-cleaning material joined by a solvent transmitting, light transmission reducing adhesive.
The magnetic heads of flexible disk systems must be cleaned periodically in order to maintain desirable performance standards. Because of the difficulty of accessing magnetic heads on flexible disk drives, various forms of cleaning disks have been developed. Initially, cleaning disks contained an abrasive lapping material to lap the magnetic heads to remove the contaminants. These cleaning disks, if used for too long, also lap the transducer head itself, causing damage to it. Such a system is disclosed in U.S. Pat. No. 4,180,840 to Allan. This system also includes a smooth surface on the face of the cleaning disk opposite the abrasive material and is constructed using heat pressure lamination.
A system similar to that disclosed in Allan is described in Canadian Patent No. 1,074,444 and U.S. Pat. No. 4,106,067, and both issued to Masuyama at al. The patents to Masuyama disclose a large variety of laminated cleaning disks with surface layer makeup varying from abrasive to nonabrasive materials laminated on a self-supporting base core. These laminated cleaning disks also have an impermeable center sheet layer. It is necessary to apply solvent to both sides of these disks in order to clean transducer heads disposed on both sides of the disk. As stated in the referenced prior art it is necessary to limit the large openings in a supporting disk jacket to one side so that the cleaning disk contained by the jacket will be supported by the other side. This makes it difficult to apply solvent to both sides.
Because of its ease of manufacture, cleaning disks formed of a single layer of fabric material have also been produced. Such disks, typically made of spun bonded polyester or olefin, are disclosed in U.S. Pat. No. 4,498,114 issued to Davis and Great Britain Patent No. 2,045,508, issued to Davis et al. These single layer fabric cleaning disks adequately hold solvent but do not withstand much wear from repeated use because of the lack of durability of the fibrous material. Further, they tend to be so translucent to the sensor light on the disk drives that they do not provide reliable operation. As a result opaque rings were developed which are adhered to or painted on fabric disks in order to provide an opaque ring which could result in reliable operation. Such cleaning disks are shown in U.S. Pat. Nos. 4,499,516 issued to Purdy et al. and 4,375,658 issued to Martinelli. These latter two patents also show the use of reinforcement rings around the spindle hole in the cleaning disk to provide for more durable construction. The adhesive used to bond or ink used to form the opaque rings on these cleaning disks leach out contaminants when solvent is applied to them. This lessens the effectiveness of the disk and even provides contaminants which may attach to a transducer head intended to be cleaned.
The head-cleaning construction art has therefore not developed a substantially full-fabric cleaning disk which is durable and opaque enough to withstand repeated use reliably.